Experimental study of slug and churn flows in a vertical pipe using plug-in optical fiber and conductance sensors

Yang, Qiuyi; Jin, Ningde; Zhai, Lusheng; Wang, D.Y.; Wang, F.

doi:10.1016/j.expthermflusci.2019.05.005

Cited by 24 publications

(13 citation statements)

References 47 publications

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“…As the mixture velocity of the gas-water flow increases, the mixture flow presents a churn flow. Deformed large bubbles randomly appear in the mixture flow [20]. Unlike the intermittent flow structure of a slug flow, the churn flow has no gas slugs that almost occupy the whole space of the pipe.…”

Section: Measurement Characteristics Of the Electromagnetic Flowmetermentioning

confidence: 99%

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Measurement of Water Velocity in Gas–Water Two-Phase Flow with the Combination of Electromagnetic Flowmeter and Conductance Sensor

Yang

Jin

Zhai

et al. 2020

Sensors

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A method to measure the superficial velocity of the water phase in gas–water flow using an electromagnetic flowmeter (EMF) and rotating electric field conductance sensors (REFCSs) is introduced in this paper. An electromagnetic flowmeter instrument factor model is built and the correlation between electromagnetic flowmeter output and gas holdup in different flow patterns are explored through vertical upward gas–water flow dynamic experiments in a pipe with an inner diameter (ID) of 20 mm. Water superficial velocity is predicted based on pattern identification among bubble, churn, and slug flows. The experimental results show that water superficial velocity can be predicted fairly accurately for bubble, churn, and slug flows with a water cut higher than 60% (absolute average percentage deviation and absolute average deviation are 4.1057% and 0.0281 m/s, respectively). The output of the electromagnetic flowmeter is unstable and invalid in slug flows with a water cut below 60% due to the non-conducting gas slug is almost filling the pipe. Therefore, the electromagnetic flowmeter is not preferred to be used in such conditions.

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Section: Measurement Characteristics Of the Electromagnetic Flowmetermentioning

confidence: 99%

“…The signal of the REFCS is used for the recurrence plot calculation. In this paper, the value of the delay time τ, embedding dimension m, and empirical coefficient α are set as 2, 3, and 0.25 [20], respectively. The recurrence plots of three typical flow patterns are shown in Figure 8.…”

Section: Flow Pattern Identificationmentioning

confidence: 99%

Measurement of Water Velocity in Gas–Water Two-Phase Flow with the Combination of Electromagnetic Flowmeter and Conductance Sensor

Yang

Jin

Zhai

et al. 2020

Sensors

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“…In these cases, the deformable and compressible gaseous phase results in a highly complex interface between the two phases [2]. These can be in the form of infinite combinations of interfacial structures like spherical, distorted, cap, slug, and churn bubbles together with ripples, huge and disturbance waves, wisps, droplets, and liquid films have been observed at different two-phase flow regimes [7], [8]. These structures show different behaviours at different flow regimes and even different axial (non-and fully-developed regions) and radial (from the pipe centre to the walls) locations of the same flow regime [8].…”

Section: Introductionmentioning

confidence: 99%

Towards Understanding the Interfacial Structures of Non-developing Slug Flow in Vertical Pipes

Holagh¹,

Ahmed²

2022

International Conference on Fluid Flow, Heat and Mass Transfer

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Non-developing slug two-phase flows in vertical pipes are widely found in various industries. These flows are of a highly complex nature largely due to the deformability of the gaseous phase resulting in unstable interfacial flow structures at different flow regimes. Such complex interfacial structures strongly control the multiphase transport phenomena including energy, mass, and momentum transfer between the phases. Therefore, a clear understanding of the behaviour characteristics of these interfacial structures is critical to the optimum design of multiphase flow systems. This study briefly provides a review on the behaviour of the gas-liquid interfacial structures for the slug flow regime in co-current upward two-phase flows. This review founds that the interfacial structures of gas-liquid interface exhibit different shapes and behaviours in non-developed compared to the fully-developed regions of slug regime. The behaviour of these structures is found to be heavily influenced by gas injector design, pipe diameter, gas and liquid phase properties, and operating flow conditions. The review also showed that the interfacial structures have been widely studied in developed region, while they have remained less understood in the non-developed region. Also, the impact of liquid and gas phases' thermo-fluid properties (density, viscosity, and surface tension) and pipe diameter on the interfacial structures in this flow regime have received the least attention.

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“…The use of optical fiber probes for the measurement of bubble velocity, bubble size distribution and bubble void fraction has become increasingly widespread and popular for use in two-phase flow detection [11][12][13][14]. However, as an invasive measurement method, the fiber probe brings potential deformation to the partial media intersection through the process of bubble piercing.…”

Section: Introductionmentioning

confidence: 99%

Influence of Bubble Deformation on the Signal Characteristics Generated Using an Optical Fiber Gas–liquid Two-Phase Flow Sensor

Zhang

Song

et al. 2021

Sensors

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The use of optical fiber probe in two-phase flow measurements is very frequently encountered, especially in the applications of chemical engineering and petroleum industries. In this work, the influence of bubble piercing signals caused by bubble deformation is studied experimentally using a laboratory-prepared wedge-shaped fiber probe in a lab-scale gas–liquid flow generator. A three-dimensional simulation model is established to study the influence of bubble deformation on the piercing signals. A theoretical analysis of the characteristics of the pre-signal influenced by the bubble deformations is undertaken for a wide range of different modeled bubble shapes. Combining the experimental and simulation results, a promising analytical method to estimate the bubble shapes by analyzing the characteristics of pre-signals is proposed. The results of this investigation demonstrate that it is possible to estimate the bubble shapes before the fiber probe contacts the bubble surface. The method developed in this investigation is therefore highly promising for reducing errors caused by deformation during the probe piercing process.

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Experimental study of slug and churn flows in a vertical pipe using plug-in optical fiber and conductance sensors

Cited by 24 publications

References 47 publications

Measurement of Water Velocity in Gas–Water Two-Phase Flow with the Combination of Electromagnetic Flowmeter and Conductance Sensor

Measurement of Water Velocity in Gas–Water Two-Phase Flow with the Combination of Electromagnetic Flowmeter and Conductance Sensor

Towards Understanding the Interfacial Structures of Non-developing Slug Flow in Vertical Pipes

Influence of Bubble Deformation on the Signal Characteristics Generated Using an Optical Fiber Gas–liquid Two-Phase Flow Sensor

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